John Snow is popularly regarded as the founder of the field of epidemiology, with his famous study of cholera in London. Snow plotted cholera cases for a neighborhood served by two wells, and found that nearly all clustered around one of the wells, the Broad St. well, where it turned out the water was contaminated. Abhaya Indrayan, author of the standard text Medical Biostatistics (and instructor of our Biostatistics courses) terms this a “natural experiment,” where the population around the Broad St. well and an alternative well was largely homogeneous, and the main difference (treatment) was the choice of well. The evidence that contaminated water was the source of the disease was clearcut, but the bacterial cause had not been discovered and skepticism persisted. Local authorities disabled the pump by removing its handle, but restored it after the epidemic subsided.
Snow, the son of a labourer, learned medicine as an apprentice, and was admitted as a member of the Royal College of Surgeons after several years working in hospitals and clinics, and before graduating from university. Snow, in addition to essentially founding the field of epidemiology, was also a pioneer in the development of anesthetics – he personally administered chloroform to Queen Victoria for the birth of her eighth child, which accelerated public acceptance of anesthetics.
Snow paid a great deal of attention to his health, and, for most of his life, was a vegetarian (eventually a vegan) and a teetotaler – a member of the York Temperance Society. Unfortunately, his body failed to recognize the benefits of these austere practices, and he died in 1858 at the age of 45. The John Snow Society, named in his honor, meets regularly in (ironically, given his abstinence from alcohol) the John Snow Pub.